Upon hearing of a summon from his father, Hephaestus returned to heaven. He had never previously met his father and they did not reunite until after Hephaestus had grown up. However, Zeus seemed to be uninterested about the reunion, instead he asked Hephaestus about the realm of Humans.
“My son, you grow up in the realm of Humans. Tell me their story.”
“They are insane. They do not fear death; instead, they will gladly exchange their lives for temporary power.”
“Why are they there?”
“Then why am I there?”
Hera, Zeus’ wife, was hiding behind the curtain. She shamefully recalled the ugly and crippled infant she gave birth to years ago. It was she who threw Hephaestus into the realm of Humans; yet, she never expected her son to return as a peerless blacksmith. Hera’s treatment of Hephaestus tainted her image, so she who firmly demanded that Zeus grant Hephaestus the realm of Humans as compensation.
“Hephaestus, how did you survive?”
“Sorrow compels one to struggle, father.”
“Stop this bickering, and let us delve straight into business. You should know that the power left by the Elder Gods in heaven has long been exhausted. Yet, in the realm of Humans...”
“I know this is why you have summoned me. Hopefully, Humans do not share our objective.”
Zeus conjured four thunderbolts and asked Hephaestus to grab the one of the left. In the blink of an eye the thunderbolt became a crackle of flames which buried itself into the realm of men, giving rise to a volcano - It was the smithy Hephaestus had always dreamt of.
“Hephaestus, my son. I know you do not want to stay in heaven. Go keep your uncle company, but always bear in mind, you are a God.”
Hephaestus agreed to what his father said and thanked him for the gift. He mentioned that he would present a gift as return before his return to the realm of men, at the same time taking something away from Zeus...
It was far before the beginning of the war between Gods and Demons when Human were living under the blessing of the Primordial Dragons. A few Gods and demons, who arrived the realm of men for all sorts of reasons, had discovered the power of the elder Gods. Later, both races sent out emissaries to observe the realm. As a result, they finally realized the existence of each other after thousands of years, foreshadowing the breakout of the war in the future.